Power transmission mineral oil base fluids



States Unite 13 Claims. (Cl. 25275) This invention pertains to improvedfunctional fluids having good lubricating properties. More particularlythis invention relates to mineral oil compositions for use in anapparatus by means of which mechanical forces are transmitted orabsorbed such as in automotive and truck transmissions, hydraulicbrakes, clutches, and various other mechanical equipment.

The smooth functioning of various power transmitting mechanismsparticularly the more complicated automotive transmissions, fluid cooledbrake mechanisms, oil lubricated wet clutches, planetary gears andhydraulic control mechanisms depends on adequate cooling and lubricationof the equipment. Rigorous requirements have been set up to qualityfluids for this service which includes wide temperature stability atboth high and low temperatures and a low pour point to insure properpumpability and fluidity at low temperatures. The fluids must not have adetrimental effect on parts with which they come in contact such asmetal surfaces e.g., copper and solid non-metallic surfaces such asorganic resins and the like. They must possess desired frictionalproperties and, in some cases extreme pressure characteristics, toafford proper lubrication of gears, clutch plates and other parts of themechanism in which they are used, such as automotive and truckequipment. Also, the fluids must not cause chattering, squawking,squealing or produce other noises caused by the frictional vibrationsand/or stick-slip phenomenon of clutch plates or other parts of suchmechanisms.

The prior art discloses various functional or power transmission fluidsof the mineral oil or synthetic type (organic esters and polyethers)containing as the improving agents, various organic phosphates, fattyacids and their esters, halogenated compounds, polymers such aspolyacrylates and the like. Compositions of this type are objectionablebecause of their inability to eliminate chattering and noises caused byfrictional vibrations and/or stick-slip phenomenon of clutch plates andthe like, particularly in equipment which is subjected to high speedsand temperatures.

-It has now been discovered that an excellent functional or powertransmission fluid is provided, which satisfactorily meets the aboverequirements, which comprises a highly refined mineral oil basecontaining an additive combination, in critical amounts, of from about0.05% to about 2%, preferably from about 0.1% to about 1% each of (1) asaturated aliphatic monocarboxylic acid having at least 18 carbon atomsin the molecule and (2) a product of neutralization between an alpihaticamine having at least 8 carbon atoms with a monoor dialiphatic acidpyrophosphate having at least 8 carbon atoms.

The long-chain aliphatic monocarboxylic acids include the saturatedfatty acids of the C to C range such as stearic, arachidic, behenic,cerotic, montanic acids and mixtures thereof. Preferred are of saturatedfatty acids having 18 to 26 carbon atoms such as stearic acid, be-.henic acid and cerotic acid and their mixtures.

The second essential additive is a product of neutraltent O."

2,961,408 Patented Nov. 22 1960 ization between an aliphatic aminehaving at least 8' carbon atoms and a monoor dialiphatic acidpyrophosphate the aliphatic group containing at least 8 carbon atoms.The aliphatic amines suitable for reaction with the aliphatic acidpyrophosphates are the primary and secondary saturated or unsaturatedaliphatic amines having from'8 to 18 carbon atoms or mixtures of suchamines. Typical of such amine reactants are octylamine, dodecylamine,tetradecylamine, hexadecylamine, octadecylamine, octadecenylamine,octadecadienylamine, dioctylamine, didoceylamine, dioctadecylamine,dioctadecadienylamine and amines derived from fatty oils or fats such ascottonseed oil, soybean oil, coconut oil; lard, tallow, and the like,such as soyamine, cocoamine, tallowamine and mixtures thereof. Amines ofthis type are marketed by Armour and C0. under the trade name Armeen andinclude Armeen 12 and 12 D (dodecylamine), Armeen 14 and 14 D(tetradecylamine) Armeen 16 and 16 D (hexadecylamine) Armeen 18 and 18 D(octadecylamine), Armeen TD (mixture of tetradecyl, hexadecyl andoctadecylamines), Armeen S and SD (mixtures of hexadecyl, octadecyl,octadecenyl and octadecadienyl amines). Preferred are the unsatu ratedamines such as octadecadienylamine or Armeen S and Armeen SD. Polyaminesare also included as reactants with the pyrophosphates. Polyamines'which are preferred are the N-alkyl alklene diamines which are preparedby the method described in U.S. 2,736,658 and and are marked by Armourand Co. under the trade name Duomeens such as Duorneen C, Duomeen S andDuomeen T, which are C1248 alkyl trimethylene dimonoand dioctylpyrophosphate, monoand didodecyl pyrophosphate, monoand ditetradecylpyrophosphate, monoand di-hexadecyl pyrophosphate, monoand di-octadecylpyrophosphate, of which preferred are monooctyl pyrophosphate dioctylpyrophosphate, monododecyl pyrophosphate, didodecyl pyrophosphate,mono-octadecyl pyrophosphate, dioctadecyl pyrophosphate and mixturesthereof.

The reaction betwen the amine and the pyrophosphate is exothermic andshould be controlled so as to prevent decomposition. Generally'thetemperature of the reaction should be between 50 and 100 C. andpreferably below C. The mol ratio of the reactants should be within theratio of 1 to 5 moles of the amine per mol of pyrophosphate compound,and preferably the reactants and reaction should be carried out undersuch conditions that the end product contains no free acid but cancontain some free amine.

The amine-acid pyrophosphate reaction products in the molar proportionsindicated in Table I were made as follows:

TABLE I Molar ratio of Temper- Example Amine Acid pyrophosphate amineature,

to pyro- 0. phosphate I Armeen SD Dioctylpyrophosphate 2/1 70 do do 5/170 do do 2.2/1 70 Octadecy Lauryl pyrophosphate 5/1 80 annne. Dodecy1-Dodecyl pyrophos- 5/1 80' amine. phate. VI DuomeenTL-Dioctylpyrophosphate 4/1 70 35% oetadecenylamine and 45%oetadecadienylamine I Duomeen T=Oi iutrimethy1ene diamine derived tromtailow.

free functional fluids should be high, as in fluids used inparking-brakes or the like, where it is desired that the frictionallevel be high enough (at least 0125 so that the force generates africtional torque level sufiicient to overcome the gravitational pull ona 30 incline. A class of additives which when added, in amounts of fromabout 0.1% to about 10%, preferably from about 0.5% to 5% by weight, tofunctional fluids of this invention, increase their static coelficientof friction to at least 0.125;; are oil-soluble alkali metal or alkalineearth metal organic sulfonates. Materials for making oil-solublesulfonates include various petroleum fractions such as minerallubricating oil fractions, alkyl-substituted aromatic compounds such asalkylated benzene or naphthalene and alkyl substituted polar-containingaromatic compounds such as alkylated phenol, naphthol, aniline, etc.Specific sulfonates which are particularly suitable for increasing thestatic coeificient of friction of functional fluids of this inventionoil-soluble sodium, potassium, calcium and barium petroleum sulfonate,tetra-tertiarybutylnaphthalene sulfonate, dinonyl naphthalene sulfonate,diwaxnaphthalene sulfonate, diwaxbenzene sulfonate, stearylbenzenesulfonate, tertiary-octylphenol sulfonate, waxphenol sulfonate andmixtures thereof. Preferred are the oil-soluble sodium, calcium and/orbarium petroleum sulfonate and dinonylnaphthalene sulfonate.

In addition to the two essential additives present in compositions ofthis invention, as well as the frictional additive (sulfonate), it ispreferred to incorporate into such compositions a small amount (0.1-5%)of specific anti-oxidants from groups (a) an oil-soluble organicthiophosphate salt of the metals of group II of the periodic tablehavingan atomic number of from 12 to 56 or (b) a mixture in about equalproportions of an alkyl phenol and an arylamine. The anti-oxidant ofgroup (a) include the group H metal salts of alkyl, aryl, alkaryl, orcycloalkyl monoand di-acid thio or dithio-phosphoric acids such ascalcium, barium or zinc alkyl, cyclo alkyl or aryl mono anddithiophosphates. Preferred compounds are calcium, barium and zincmethylphenyl dithiophosphate, dimethyl cyclohexyl dithiophosphate,dihexyl dithiophosphate, lauryl benzyl dithiophosphate and mixturesthereof. Compounds of this type are available commercially under thetrade names of Lubri-Zol 66, 304, 360 or 1060 (Lubri-Zol Corp.);Aerolube 70 (American Cyanamid Co.) and Stan-Add 71 (Standard Oil Co. ofIndiana). A particularly preferred class of such compounds includes theZn and Ba salts of dimethylcyclohexyl dithiophosphate, Ba salt of P Spolybutene reaction products and/ or P s -terpene (pinene) reactionproducts. Such products are commercially available from Lubri-ZolCorporation, Standard Oil Company of Indiana and Monsanto ChemicalCompany, respectively, under the above indicated trade names.

The anti-oxidant mixture of group (b) include alkyl phenols, e.g., diand tri alkylphenols, for instance 2,4-, 2,3-, 3,4-, 2,6- and 3,5-diamylphenol, 2,4-dimethyl-6- tertbutyl phenol, 2,6-ditertbutyl-4-methylphenol; and arylamines such as phenyl-a-naphthylamine, or phenyl-B-naphthylamine.

Also optional additives can be used in compositions of this inventionsuch as anti-foaming agent e.g., silicone polymers (DC 200 fluids)ranging in viscosity in centistokes from 100 to 1000 at 25 C. orSilicone Type A fluid made by DowCorning Co. and described in US.Patents 2,563,588 and 2,662,055. These optional agents when used incompositions of this invention are employed in amounts of from 0.0001%to 10% and preferably between 0.l% and 5%.

The base oil is a hydrocarbon oil preferably of wide viscosity range andhaving a high viscosity index and a low pour point. These oils can rangein viscosity from 40 l SUS at F. to SUS at 210 F., and include mineralspray oil, transformer oil as well as lubricating oils having SAEnumbers of 10, 20, 30, etc. Oils of this type have the followingproperties:

SAE 10 mineral oil Viscosity, SUS, at 100 F Viscosity, SUS, at 210 F45.2 Viscosity index 106, Flash, 9 F 395 Fire, F- 440 Pour point, F -35Another suitable base oil is a refined, highly refined transformer oil(A) having the following properties:

Sp. gr., API 30.9 Color V 30 Viscosity, SUS, at 100 F 56.9 Flash, COC, F290 Fire, COC, F 320 Pour point, F Below --70 Still another suitablebase oil is a refined mineral oil (B) having the following properties:

Sp. Gr., API 31.2 Color, ASTM -1 Pour point ---30 Flash, F 270 Fire, F295 Viscosity, SUS, at 100 F 48 Viscosity index 33 The followingcompositions are illustrative of the present invention.

Composition A Stearic acid percent wt 0.2

Example I additiv do 0.2 Calcium petroleum sulfonate do 5 Zinc dimethylcyclohexyl dithiophosphate.... do 0.5 Dimethyl silicone polymer (1000cs. at 25 C.) p.p.m- 5 Mineral oil (B) Balance Composition B Stearicacid percent Wt 0.2

Compositions of this invention eliminate noise, frictional vibrationsand stick-slip sliding in various equip ment such as liquid cooledhydraulic brake systems in which the friction members were made of steeland resilient, or semi-metallic, or full sintered metallic frictionmaterials. Evaluation was done in actual automobile tests wherein thenoise created after accelerating and suddenly stopping the vehicle wasrated, 10 being excellent, no noise or stick-slip and zero (0) beingpoor, severe noise and stick-slip.

With compositions A, B, C, and D the ratings were between 8 and 10.Mineral oils (A) and (B), each containing 0.2% stearic acid, or 0.2%cerotic acid gave ratings of 4 and 5 respectively, whilethe same oilseach containing 0.2% stearic acid and 5% Lubri-Zol66 gave ratings of 5.Transformer oil (A) or mineral oils (B) each containing 0.5% of n-octylacid phosphate, dioctyl phosphate and triisooctyl phosphate gaveratingsof 4, 1 and 1, respectively, while transformer oil (A) containing0.4% lauryl acid phosphate gave a rating of 3 and transformer oil (A)containing 0.2% lauryl acid phosphate and 2.5% Lubri-Zol 1060 gave arating of 1.

The static coetficient of friction of Compositions B, C and D was about0.04 whereas the static coefficient of friction of Composition Acontaining 2.5% neutral calcium petroleum sulfonate increased thecoefficient of friction to 0.130 The addition of 2.5% of neutral calciumdinonylnaphthalene sulfonate or barium dinonylnaphthalene sulfonate, orneutral calcium petroleum sulfonate to Composition C increased thestatic coefiicient of friction of the compositions from 0.0411. to15211., 1.88 1 and 1.42,, respectively. These values are far above therequired minimum of 0.125 1. On the other hand, the addition of 2.5% ofcalcium naphthenate, or calcium C1448 alkyl salicylate, or zincdimethylcyclohexyl dithiophosphate or tricresyl phosphate to CompositionC gave static coeflicient of friction values of 0.086 0.49 0052 1 and0.091 respectively. These values are below the required minimum of 0.125

Thus the data shows the outstanding properties which compositions ofthis invention possess with respect to eliminating noise and stick-slipin brake systems. On the other hand, mineral oils containing a fattyacid, e.g., stearic or cerotic acids alone or in combinationthiophosphates or mineral oils containing various acid phosphates aloneor in combination with a metal thiophosphate gave poor results. Also thedata shows that the static coeflicient friction of compositions of thepresent invention can be increased to a desired value by addition tosuch compositions certain oil-soluble sulfonates and that other metalsalts e.g. naphthenates or salicylates or phosphate esters are noteffective when used for this purpose in compositions of this invention.

We claim as our invention:

1. A noise-free power transmission fluid consisting essentially of amajor amount of a refined mineral lubricating oil and from about 0.05%to about 2% each of an aliphatic monocarboxylic acid having from 18 to26 carbon atoms in the molecule and a reaction product prepared byreacting from 1 to 5 moles of an aliphatic amine having from 8 to 18carbon atoms with a mol of an aliphatic acid pyrophosphate having from 8to 18 carbon atoms until the reaction is substantially completed, thereaction being carried out at a temperature below that at whichsubstantial decomposition of the reaction product occurs.

2. A noise-free power transmission fluid consisting essentially of amajor amount of a refined mineral lubrieating oil and from about 0.05%to about 2% each of a saturated fatty acid having from 18 to 26 carbonatoms in the molecule and a reaction product prepared by reacting from 1to 5 moles of a C aliphatic amine with a mol of an aliphatic acidpyrophosphate having from 8 to 18 carbon atoms until the reaction issubstantially completed, the reaction being carried out at a temperaturebelow that at which substantial decomposition of the reaction productoccurs.

3. A noise-free power transmission fluid consisting essentially of amajor amount of a refined mineral lubricating oil and from 0.05 to about2% each of a saturated fatty acid having from 18 to 26 carbon atoms inthe molecule and a reaction product prepared by reacting from 1 to 5moles of a C alkyl amine with a mol of an alkyl acid pyrophosphatehaving from 8 to 18 carbon atoms until the reaction is substantiallycompleted, the reaction being carried out at a temperature below that atwhich substantial decomposition of the reaction product occurs.

4. A noise-free power transmission fluid consisting essentially of amajor amount of'a refined mineral lubricating oil and from about,0.05%to about 2% each of stearic acid and a reaction product of a C aliphaticamine with 21 mol of an alkyl pyrophosphate having from 8 to 18 carbonatoms until the reaction is substantially cornpleted, the reaction beingcarried out at a temperature below that at which substantialdecomposition of the reaction product occurs, '5. A noise-free powertransmission fluid consisting essentially of a major amount of a refinedmineral lubricating oil and from about 0.05% to about 2% each of stearicacid and a reaction product prepared by reacting from 1 to 5 moles of aC aliphatic amine with a mol of octyl pyrophosphate until the reactionis substantially completed, the reaction being carried out at atemperature below that at which substantial decomposition of thereaction product occurs.

6. A noise-free power transmission fluid consisting essentially of amajor amount of a refined mineral lubricating oil and from about 0.05 to2% each of stearic acid and a reaction product prepared by reacting fromIto 5 moles of a C aliphatic amine with a mol of dioctyl pyrophosphateuntil the reaction is substantially completed, the reaction beingcarried out at a temperature below that at which substantialdecomposition of the reaction product occurs.

7. A noise-free power transmission fluid consisting essentially of amajor amount of a refined mineral lubricating oil and from about 0.05 to2% each of cerotic acid and a reaction product prepared by reacting from1 to 5 moles of a C aliphatic amine with a mo] of an alkyl pyrophosphatehaving from 8 to 18 carbon atoms until the reaction is substantiallycompleted, the reaction being carried out at a temperature below that atwhich substantial decomposition of the reaction product occurs.

8. The power transmission fluid of claim 1 containing from about 0.1% toabout 10% of an oil-soluble metal organic sulfonate the metal portion ofthe salt being selected from the group consisting of alkali and alkalineearth metals.

9. The power transmission fluid of claim 4 containing from about 0.1% to10% of oil-soluble calcium petroleum sulfonate and from about 0.1 toabout 5% of oil-soluble zinc cycloalkyl dithiophosphate.

10. The power transmission fluid of claim 5 containing from about 0.1%to 10% of oil-soluble sodium petroleum sulfonate.

11. A noise-free power transmission fluid consisting essentially ofabout 0.2% stearic acid, about 0.2% of a reaction product prepared byreacting from 1 to 5 moles of C C aliphatic amine with a mol of dioctylpyrophosphate until the reaction is substantially completed, thereaction being carried out at a temperature below that at whichsubstantial decomposition of the reaction product occurs, and about0.1-0.5% of a mixture of an alkyl phenol and an aryl amine and thebalance being a refined transformer mineral oil.

12. A noise-free power transmission fluid consisting essentially ofabout 0.2% stearic acid, about 0.2% of a reaction product prepared byreacting from 1 to 5 moles of C1648 aliphatic amine with a mol ofdioctyl pyrophosphate until the reaction is substantially completed,

aliphatic amine with a mol of dioctyl pyrophosphate until the reactionis substantially completed, the reaction being carried out at atemperature below that at which substantial decomposition of thereaction product occurs, about 7 2.5-5% calcium petroleum sulfonate,about 0.5% zinc dimethylcyelohexyl di thiophosphate, and about 5 p.p.m.dimethyl silicone polymer and the balance being a refined transformermineral oil.

References Cited in the file of this patent UNITED STATES PATENTS2,005,619 Graves June 18, 1 935 8 Benniug May 11, 1937 Baker Aug. 24,1948 Watson May 30, 1950 Rudel Apr. 29, 1952 Woodstock et a1. Dec. 29,1953 Watson Aug. 17, 1954 Jones Nov. 9, 1954 Wasson et a1. Apr. 15, 1958Chenicek Aug. 19, 1958

1. A NOISE-FREE POWER TRANSMISSION FLUID CONSISTING ESSENTIALLY OF AMAJOR AMOUNT OF A REFINED MINERAL LUBRICATING OIL FROM ABOUT 0.05% TOABOUT 2% OF EACH OF AN ALIPHATIC MONOCARBOXYLIC ACID HAVINNG FROM 18 TO26 CARBON ATOMS IN THE MOLECULE AND A REACTION PRODUCT PREPARED BYREACING FROM 1 TO 5 MOLES OF AN ALIPHATIC AMINE HAVING FROM 8 TO 18CARBON ATOMS WITH A MOL OF AN ALIPHATIC ACID PYROPHOSPHATE HAVING FROM 8TO 18 CARBON ATOMS UNTIL THE REACTION IS SUBSTANTIALLY COMPLETED, THEREACTION BEING CARRIED OUT AT A TEMPERATURE BELOW THAT AT WHICHSUBSTANTIAL DECOMPOSITION OF THE REACTION PRODUCT OCCURS.